LTspice stepping build-In Opamp models


I want to do a simulation with a .step command where I can exchange the simulated opamp. I want to do a parametric noise calculation. So I found on the web that there is a ako command to map models to numbers and then stepping the numbers. But in my case I've the problem that it comes with unknown subcurcuit call. 

Is there a way to do this job in LTSpice? Which symbols do I have to use on .asc file?